Methods of preparing cyano phosphine oxides



United tates ate t hicfi 3,3432% Patented Sept. 8, 1964 3,148,206METHQDS F PREKARTNG CYANG PHGSPEWE @XTDES Michael McKay Rauhut,Norwallr, and Andrew ll liio Sen-reel, Stamford, Conn, assignors toAmerican Cyanamid Compan Stamford, Conn, a corporation of Maine NoBrewing. Filed Mar. 4, 1963, Ser. No. 262,306 3 Claims. (Ci. Zed-465.8)

The present invention relates to organophosphorous compounds and to thepreparation of same. More par ticularly, the instant discovery concernsthe preparation of tertiary phosphine oxides by a novel andstraightforward method.

Heretofore, tertiary phosphine oxides of the general type contemplatedherein have been prepared by a twostep process whereby the tertiaryphosphine is first formed and then oxidized to its correspondingtertiary phosphine oxide. Pursuant to the instant discovery, a singlestep procedure has been discovered whereby tertiary phosphine oxides ingenerous yields are produced. As will be seen hereinafter, this is asignificant contribution.

According to present invention an amt-unsaturated compound of theformula Z Y NCC T=CH wherein Z and Y have the meaning given above.

Pursuant to a typical embodiment of the present invention the followingreaction is made to take place:

P +Cl-L CHCN{KOH+H O (crtca cnp ro -xn ro While the elemental phosphorusreactant employed in the equation just given is in a finelyivided solidstate, the present invention contemplates the use of molten phosphorus,and therefore temperatures above the melting point of phosphorus, i.e.,temperatures above 46 C. In fact, a wide range of temperatures iscontemplated herein on the order of about 0 C. to about 175 C.,preferably from 15 C. to 75 C.

By the same token, the reactions of the present invention may be carriedout at atmospheric, sub-atmospheric and super-atmospheric pressures, Athigh temperatures, say, from 100 C.-175 C., super-atmospheric pressuresare generally employed, as is evident to the person skilled in the art.Batch, continuous or semi-continuous processes may be employed.

According to a preferred embodiment of the instant discovery, an aqueousstrong base is employed. Typical bases within the purview of the presentinvention are the alkali metal hydroxides, and carbonates, the alkalineearth metal hydroxides, and carbonates, quaternary ammoni m hydroxides,tetramethylguanidine, pentamethylguanidine, heptamethylbiguanide, andthe like. If desired, reaction is made to take place in the presence ofa solvent. Typical solvents are acetonitrile, a tertiary alcohol, suchas t-butyl alcohol, an ether, such as dioxane, diethoxyethane,diethylether of diethylene glycol, tetrahydrofuran, and the like,dimethylformamide, dimethylsulfoxide, pyridine and numerous other likesolvents, which under the conditions of the reaction do not interferewith the production of the desired products.

Typical mil-unsaturated nitrile reactants of the formula Z Y N C(|3=('3Habove, are acrylonitrile, methacrylonitrile, crotononitrile,cinnamonitrile, a-methyleneglutaronitrile, and the like.

Generally, the reactants contemplated herein are brought together instoichiometric amounts. However, an excess of any of these reactantswith respect to the remaining reactant may be employed and the amount ofexcess is governed by practicality.

The products of the present invention are useful as fire retardants forcotton cloth. For example, cotton cloth dipped, according to well-knownprocedures, in a suitable solution of any one of these tertiaryphosphine oxides manifests desirable fire retardance.

The present invention will best be understood by virtue of the followingexamples which are merely illustrative and not intended to limit thescope of the invention, except insofar as the invention is described inthe claims.

EXAMPLE I T ris(2-Cyan0ethyl )Phosphine Oxide A mixture of 7.7 grams(0.25 gram atom) of white phosphorus, 29.7 grams (0.56 mole) ofacrylonitrile, and milliliters of acetonitrile is warmed to 50 C. in acreased flask under nitrogen. The mixture is stirred vigorously andcooled to 30 C. so that the phosphorus solidifies in a finely dividedstate. To this mixture is added dropwise with vigorous stirring 18.0milliliters (0.18 equivalents) of 10 N aqueous potassium hydroxideduring 20 minutes. The temperature is maintained at 30 C.35 C. bycooling. The mixture is stirred one additional hour at this temperature.By the end of the reaction period a dense white solid has separated. Thereaction mixture is diluted with a solution of 10 milliliters ofconcentrated hydrochloric acid in 300 milliliters of water. The soliddissolves giving a neutral solution containing only traces of unreactedwhite phosphorus. The mixture is warmed to 50 C. to melt the phosphorus,cooled to room temperature, and the solution is decanted under nitrogen.The solution is filtered through diatomaceous earth and evaporated todryness under reduced pressure. The residue is extracted with 200milliliters of hot methanol. The extract when cool deposits 23.5 grams(45 percent) of tris(Z-cyanoethyDphosphine oxide, melting point C.-169C. Concentration of the filtrate gives an additional 4.5 grams (9percent), melting point 165 C. 169 C. Recrystallization from aqueousisopropyl alcohol gives material melting at 172 C.-l73 C. (lit. meltingpoint 172 C.-173 C.) which does not depress the melting point of anauthentic sample. Results of similar experiments are presented in TableI.

EXAMPLES II-V The following examples are carried out essentially as inExample 1, above; the differences existing between the followingexamples and Example I are set out in the table:

wherein Z is a member selected from the group consisting of H, CH and CHCH CN and Y is a member selected from the group consisting of H, CH andphenyl, which comprises reacting, at a temperature in the range of aboutTABLE I Example Beactant Solvent Base Temper- Product ature, C.

II Methacrylonitrile. CH; ON NaOH 75-80 (111 (NCOHGH2)3 P II IOrotononitrile D imethyliormamide KOH 75-85 (IJH (NCCHz (II-D3 P =0 IVo. -Methylenegluta- OH; ON Ca(OH) 2 75-80 ON ronitrile.

(NCCI-I2 CH1 OHCHm P =0 V Cinnamonitrile CH3 CN Ba(0H)z 75-85 (NCCH2CHCI-I P=0 VI Acrylonitrile Acetonitrile KzCOa 25-35 (NCCI'I2CI'I2)3 P: O

VII Methacrylonitrile t-butanol CaC O3 75-85 (IJH (NOSE-0112):; P 0

VIII Crotononitrile Acetonitrile 'letrabeuzyl-amrnonium 25-35 CHhydroxide.

(NCCHz (DI-D3 I =0 IX a-Methylenegluta- 'IetrahydroiuranBenzyltrimethyl-ammo- 45-50 ON ronitrile. nium hydroxide.

(NCCHzGHzCHOHz)a P=0 X Cinnamonitrile Dioxane Tetramethyl-guanidine -30(NC CH2 GI-IC H 3 P O XI Acrylonitrile Pyridine Pentametliyl-guanidine30-40 (N 0 CH2 0111);; P O

XII. Methacrylonitrile. Diethylether of di- Heptamethyl-biguanide- 30-40CH ethylene glycol.

(NOCHCH2)3 I O XIII. Aerylonitrile Acetonitrile Hexamethyl-biguanide.-35 (N O CH OH P O XIV Ginnamonitrile Dioxane Tt ra metlcilyl-ammonium20-30 (N OCH; CHC Hm P 0 y roxi e. XV Acrylonitrile PyridineTetrabutyl-ammonium -40 (NCOHZ CH P=0 hydroxide. XVI do d0Tribenzyl-mcthylammo- 30-40 (NCGH (311m 1? 0 nium hydroxide.

As is evident from Table I, above, tetraalkylflower) ammoniumhydroxides, benzylalkyl(lower) ammonium hydroxides, hexaalkyl(lower)-and heptaalkyl(lower)- biguanides, broadly, are contemplated herein.

Clearly, the instant discovery encompasses numerous modifications withinthe skill of the art. Consequently, while the present invention has beendescribed in detail with respect to specific embodiments thereof, it isnot intended that these details be construed as limitations upon thescope of the invention, except insofar as they appear in the appendedclaims.

This application is a continuation-in-part of pending US. applicationSerial No. 101,353, filed April 7, 1961, now abandoned.

We claim:

1. A method of preparing a tertiary phosphine oxide of the formula 0 C.to about C., elemental phosphorus, a strong base, and water, in thepresence of an inert organic solvent and with an one-unsaturatedreactant of the formula No references cited.

UNITED STATES PATENT OFFICE 1 CERTIFIQATE 0F CORRECTION Patent No. 3,148,206 September 8 1964 Michael McKay Rauhut et a1. It is herebycertified that error appears in the above numbered pats Patent shouldread as ent requiring correction and that the said Letter correctedbelow Columns 3 and 4 TABLE I, under the heading Opposite Example 111the formula should appear as s instead of as in the patent:

"Product" and hown below (NCCH CH) P O Signed and sealed this 30th dayof March 1965a (SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Aitesting Officer Commissioner ofPatents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No3,148,206 September 8 1964 Michael McKay Rauhut et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Columns 3 and 4, TABLE I, under the heading "Product" and oppositeExample III the formula should appear as shown below instead of as inthe patent:

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER AitestingOfficer

1. A METHOD OF PREPARING A TERTIARY PHOSPHINE OXIDE OF THE FORMULA